Application of micro techniques for measurement of pressure velocity, flow, dimensions and vessel hematocrit using intravital microscopy of tissues such as the mesentery, omentum, skeletal muscle in laboratory animals. Goal is to develop analytical solutions for regulation of transport and exchange functions of particular microcirculatory beds. Studies include normal circulation as well as the effects of hemorrhage and bacterial endotoxemia. Regulation of pressure in capillary network is achieved primarily by myogenic type of auto regulation on precapillary side of the microcirculation. Pressure distribution suggest filtration of fluid at rate reflected by lymph flow from region. The actual pressure drop is effected by branching junctions in the arteriolar region. Flow through the microscopic blood vessels is affected more by the behavior of the cellular elements than by the diameter of the capillary vessels.